1. Field of Invention
The field of the currently claimed embodiments of this invention relates to magneto-electronic devices and methods of production, and more particularly to magneto-electronic devices that include an electric-field-controllable magnetic tunnel junction and methods of production.
2. Discussion of Related Art
Magnetic tunnel junctions (MTJs), particularly MgO-MTJs with large tunnel magnetoresistance (TMR), are leading devices for field sensing, nonvolatile magnetic random access memories (MRAMs) and spin logic applications1-5. It has been predicted that the electric field can substantially alter the interfacial magnetic anisotropy energy and even induce magnetization reversal in 3d transition ferromagnets (FMs) 6-10, which could possibly provide a more energy efficient route to manipulate the magnetization in MTJs when compared with the spin transfer torque (STT) effect 11. Indeed, driven by the premise that voltage-controlled switching would be far more energy saving and compatible with the ubiquitous voltage-controlled semiconductor devices12-15, many studies have been focused on multiferroic materials16-17, such as electric field controlled spin-polarization18, antiferromagnetic order19, and electrostatically tunable ferromagnetic resonance20. However, multiferroic materials (e.g. BiFeO3, BaTiO3) are not utilized in spintronics devices. Electric field controlled magnetism has also been demonstrated in diluted magnetic semiconductors such as (Ga,Mn)As and (In,Mn)As, where the ferromagnetism, due to a very different mechanism, is mediated by the carriers.15 The modification of the carrier density by a gate voltage can result in a change of Curie temperature21, coercivity22 and magnetic anisotropy13, but the very low Curie temperature (<200K) is a serious shortcoming.
Recently, it has been shown that the coercivity HC of metallic ferromagnetic FePt and FePd films can be modified by up to 4% through the electric field applied at the electrolyte-film interface.23 This result has triggered intense interest in electric field controlled magnetism in 3d FMs. Subsequently, electric field induced modification of magnetic anisotropy of a single Fe film in all-solid samples has been reported,24 and further investigated by Brillouin light scattering,25 Kerr effect,26 ferromagnetic resonance27 and anomalous Hall effect28. However, the essential feature of resistance switching induced by an electric field has not been realized yet. There thus remains a need for improved magneto-electronic devices.